9,161 research outputs found

    Can a profession exist without research?

    Get PDF
    Radiography combines science, technology and patient care to provide an essential role in medical diagnosis and treatment. The term ‘profession’ has existed in the Oxford English Dictionary from the 15th century and argues that a profession is an occupation where professional knowledge is applied by someone who has undertaken prolonged training and obtained a formal qualification (Oxford English Dictionary Online; 2007). For most of history, professions have based their practices on expertise derived from experience passed down in the form of tradition. Even in health care, many practices have still not been justified by evidence and as such there are areas of uncertainty.peer-reviewe

    Morphogen Gradient from a Noisy Source

    Full text link
    We investigate the effect of time-dependent noise on the shape of a morphogen gradient in a developing embryo. Perturbation theory is used to calculate the deviations from deterministic behavior in a simple reaction-diffusion model of robust gradient formation, and the results are confirmed by numerical simulation. It is shown that such deviations can disrupt robustness for sufficiently high noise levels, and the implications of these findings for more complex models of gradient-shaping pathways are discussed.Comment: Four pages, three figure

    Study of techniques for the reduction of creep in plated wire memories Final report, 28 Jun. 1967 - 28 Aug. 1968

    Get PDF
    Magnetization reversal in thin films of plated wire memory element

    Models of the diffuse radar backscatter from Mars

    Get PDF
    The topographies of several debris flow units near the Mount St. Helens Volcano were measured at lateral scales of millimeters to meters in September 1990. The objective was to measure the surface roughness of the debris flows at scales smaller than, on the order of, and larger that the radar wavelength of common remote sensing radars. A laser profiling system and surveying instruments were used to obtain elevation data for square areas that varied in size from 10 to 32 cm. The elevation data were converted to estimates of the power spectrum of surface roughness. The conversions were based upon standard periodogram techniques, and upon a modified spectral estimation technique that was developed

    Truth Table Invariant Cylindrical Algebraic Decomposition by Regular Chains

    Get PDF
    A new algorithm to compute cylindrical algebraic decompositions (CADs) is presented, building on two recent advances. Firstly, the output is truth table invariant (a TTICAD) meaning given formulae have constant truth value on each cell of the decomposition. Secondly, the computation uses regular chains theory to first build a cylindrical decomposition of complex space (CCD) incrementally by polynomial. Significant modification of the regular chains technology was used to achieve the more sophisticated invariance criteria. Experimental results on an implementation in the RegularChains Library for Maple verify that combining these advances gives an algorithm superior to its individual components and competitive with the state of the art

    The unique N-terminal sequence of the BKCa channel α-subunit determines its modulation by β-subunits

    Get PDF
    Large conductance voltage- and Ca2+-activated K+ (BKCa) channels are essential regulators of membrane excitability in a wide variety of cells and tissues. An important mechanism of modulation of BKCa channel activity is its association with auxiliary subunits. In smooth muscle cells, the most predominant regulatory subunit of BKCa channels is the β1-subunit. We have previously described that BKCa channels with distinctive N-terminal ends (starting with the amino acid sequence MDAL, MSSN or MANG) are differentially modulated by the β1-subunit, but not by the β2. Here we extended our studies to understand how the distinct N-terminal regions differentially modulate channel activity by β-subunits. We recorded inside-out single-channel currents from HEK293T cells co-expressing the BKCa containing three N-terminal sequences with two β1-β2 chimeric constructs containing the extracellular loop of β1 or β2, and the transmembrane and cytoplasmic domains of β2 or β1, respectively. Both β chimeric constructs induced leftward shifts of voltage-activation curves of channels starting with MANG and MDAL, in the presence of 10 or 100 μM intracellular Ca2+. However, MSSN showed no shift of the voltage-activation, at the same Ca2+ concentrations. The presence of the extracellular loop of β1 in the chimera resembled results seen with the full β1 subunit, suggesting that the extracellular region of β1 might be responsible for the lack of modulation observed in MSSN. We further studied a poly-serine stretch present in the N-terminal region of MSSN and observed that the voltage-activation curves of BKCa channels either containing or lacking this poly-serine stretch were leftward shifted by β1-subunit in a similar way. Overall, our results provide further insights into the mechanism of modulation of the different N-terminal regions of the BKCa channel by β-subunits and highlight the extension of this region of the channel as a form of modulation of channel activity

    Radiological Characterization of a Uranium Processing Facility

    Get PDF
    This document describes the plan that was developed and is being carried out at the Oak Ridge Y-12 Plant to provide data needed for radiological characterization of the site in anticipation of new posting regulations provided in Title 10, Code of Federal Regulations, Part 835, as codified from Volume 58, Number 238 of the Federal Register. The characterization plan addresses the entire site in terms of three categories: 1) Outdoor paved surfaces, 2) buildings, and 3) outdoor non-paved surfaces. Instruments chosen for use in this project are described, as well as survey techniques and the data management scheme. A quantitative assessment of the effectiveness and adequacy of the survey plan for paved surfaces is also provided

    Generalised Elliptic Functions

    Full text link
    We consider multiply periodic functions, sometimes called Abelian functions, defined with respect to the period matrices associated with classes of algebraic curves. We realise them as generalisations of the Weierstras P-function using two different approaches. These functions arise naturally as solutions to some of the important equations of mathematical physics and their differential equations, addition formulae, and applications have all been recent topics of study. The first approach discussed sees the functions defined as logarithmic derivatives of the sigma-function, a modified Riemann theta-function. We can make use of known properties of the sigma function to derive power series expansions and in turn the properties mentioned above. This approach has been extended to a wide range of non hyperelliptic and higher genus curves and an overview of recent results is given. The second approach defines the functions algebraically, after first modifying the curve into its equivariant form. This approach allows the use of representation theory to derive a range of results at lower computational cost. We discuss the development of this theory for hyperelliptic curves and how it may be extended in the future.Comment: 16 page

    One Instructional Leadership Team’s Journey through a Professional Learning Cycle

    Get PDF
    Schools often set a large number of goals, making it difficult to plan, support, monitor, and match strategic levers in a systematic way. This study narrates the actions and findings of one instructional leadership team as they implement an eight week cycle of professional learning around a single focus. Scripted observations of teachers and students, achievement data, student work samples, as well as exit slips with action items recount the team members’ perspectives and experiences. The team chronicled its journey, which proved to be one of inquiry, trial and error, reflection and retooling. The study closes with highlighting the changes in both teachers’ instructional practices and school-wide improvement systems, the challenges and benefits, and the researcher’s interpretations and implications for school staffs
    • …
    corecore